As release coating, silicone compositions have been used to render adhesive materials nonadherent to substrates. Such silicone compositions generally comprise a mixture of an ethylenically-unsaturated organopolysiloxane, an organohydrogenpolysiloxane, and a catalyst for the curing of the mixture by means of a hydrosilation reaction.
For example U.S. Pat. No. 4,609,574 discloses a curable silicone coating composition that cures more rapidly at elevated temperatures or cures less rapidly at lower temperatures. This composition comprises (A) a polydiorganosiloxane wherein 90 to 99.5% of all organic groups are methyl and from 0.5 to 10% of all organic groups are selected from vinyl and higher alkenyl groups, (B) an effective amount of a metal hydrosilation catalyst; (C) a methylhydrogenpolysiloxane crosslinking agent compatible with (A) and having an average of at least three silicon-bonded hydrogen atoms per molecule; and (D) an effective amount of an inhibitor for the metal hydrosilation catalyst; and wherein the composition contains 0.8 to 1.5 silicon-bonded hydrogen atoms for every unsaturated group in the composition.
While silicone compositions that provide coatings having low release and fast curing characteristics are known, silicone compositions that provide release coatings which do not require catalysts are sought.
As pressure-sensitive adhesives, silicone compositions are known. They have a variety of applications because they can possess one or more of the following properties: high thermal stability; high oxidative stability; permeability to many gases; low surface energy; low index of refraction; low hydrophilicity; dielectric properties; biocompatibility; and adhesive properties. Examples of such pressure sensitive adhesives are disclosed in U.S. Pat. No. 5,461,134 (Leir et al.), U.S. Pat. No. 5,512,650 (Leir et al.), U.S. Pat. No. 5,475,124 (Mazurek et al.), U.S. Pat. No. 5,792,554 (Leir et al.), U.S. Pat. No. 6,355,759 (Sherman et al.) and U.S. Pat. No. 6,458,454 (Kreckel).
Although silicone pressure sensitive adhesives are known to adhere to a wide variety of substrates, there is still a need for adhesives and adhesive articles, particularly tapes that provide an effective peel strength and shear strength to such substrates, without the need for a catalysts or other chemical or physical surface treatment of the substrate. Further, the composition may be prepared neat or in a solvent, and applied to a substrate using a solvent or hot-melt coated.